For standard American television transmission the intensity video information is limited to a bandwidth of 4 MHz, with the remainder of a 6 MHz channel being used for the lower vestigial sideband and the audio transmissions. The audio transmissions are modulated on a standard 4.5 MHz carrier within the channel.
It is desirable to provide a level of security in cable television transmission so that the video and/or audio segments of a transmission may only be viewed and/or heard on a premium basis by subscribers who have paid a special fee (premium) therefor.
U.S. Pat. No. 4,402,010 discloses a television signal processing and transmission system.
Commonly-owned U.S. Pat. No. 4,646,150 discloses APPARATUS AND METHOD FOR STEREO TELEVISION SOUND, and is referenced to show television audio transmission and reception techniques.
Commonly-owned U.S. Pat. No. 4,628,358 and U.S. patent application Ser. No. 022,380, filed on Mar. 5, 1987, now U.S. Pat. No. 4 821 097, describe various techniques for scrambling television transmissions, and descrambling the transmissions at the subscriber end of the cable network. These techniques, although effective, are typically complex, and relatively costly to implement.